This study meets the information hydrogeological of aquifer Casma - Sector San Rafael, in this sector of water resources demands are not covered by surface water, making it necessary to resort to the use of groundwater as a means of mitigating deficit presented. The overall objective was to evaluate the conditions of availability and use of groundwater in the aquifer in question, for which the updated inventory and monthly monitoring wells throughout 2014 in 26 observation wells was carried out in addition to the collection geological, geophysical data, groundwater levels, physical and chemical analysis and testing of pumping allowed by its analysis to characterize the aquifer. The surface source in this area consists of the discharge of the river Casma which have a tendency to decrease according to the analysis, the other source is the Casma aquifer, where the depth of the groundwater levels are falling between 0.50 m and 20 m. According to the results of monitoring of water levels in all cases obey the behavior of the hydrological cycle, with promotions and recovery water levels between April and July and the decline or depression, from November to December, but on a fluctuating near the P-2 and P-4 surface wells, levels have failed to recover, mainly explained by the large volumes of extraction wells in the area. Based on pumping tests and physical-chemical analysis is characterized as an aquifer with good yields and quality of water suitable for agricultural use. Finally, the total surface water reserves stored in the aquifer has been estimated for the present study 33.04 MMC, MMC 4.66 which corresponds to renewable reserves and 11.01 MMC usable volume, based on this result is possible to plan the volume rational exploitation of groundwater also manage the aquifer so that user requirements are met